Ultrafast coherent 2D fluorescence micro-spectroscopy on semiconducting carbon nanotubes at room temperature

Abstract

Further developments in nano- and molecular electronics would benefit strongly from the possibility of the spatio-temporal evolution of molecular processes. Non-linear ultrafast techniques provide insights into energy transfer pathways, e.g., mediated via electronic coupling. A comprehensive way to observe these dynamics is ultrafast coherent 2D fluorescence micro-spectroscopy [1]. This method is a generalization of transient absorption spectroscopy with frequency resolution both for the pump and the probe step, combined with spatial resolution in an optical microscope. This provides the capability to observe, e.g., inhomogeneous line broading as well as the formation and annihilation dynamics of excitons on the femtosecond timescale. Here, we utilize the third-order 2D signal for monitoring electronic coupling and energy transfer processes in semiconducting single-walled carbon nanotubes. To this end, an LCD-shaped four pulse sequence with 13 fs temporal encoding of each puls is focused through an NA = 1.4 objective and the fluores-cence is detected as a function of inter-pulse time delays and phases. [1] S. Goetz, et al., Optics Express 26, Nr. 4: 3915-25 (2018)</p